Interface-based DesignOutlineOrthogonalization of ConcernsSlide 4Required ToolsFormalism – Models of ComputationRefinement (Abstraction-1)(De)compositionDesign ExampleCheetah SimulatorCheetah Simulator (II)Future InroadsFuture Inroads (II)Interface-based DesignInterface-based DesignDonald ChaiEE249OutlineOrthogonalization of concernsFormalismsInterface-based Design ExampleCheetah SimulatorFuture InroadsOrthogonalization of ConcernsBehavior (or computation, coordination)Communication (or interfaces)These two are (or should be) independentInterface-based DesignDone all the timeOSI stackMemory mapped I/OVirtual memoryRequired ToolsA good formalism with which to perform:Abstraction (and hierarchy)Decomposition (and composition)These concepts exist for both computation and communicationFormalism – Models of ComputationAll models of computation specify a set of actors and a communication mechanismFSMs – synchronous compositionCFSMs – event broadcastDataflow/KPN – lossless queuesCSP – rendezvousSome models conflate communication and computationRefinement (Abstraction-1)1. Simple channel through which tokens are passed2. REQ/ACK protocol•Master requests, slave acknowledges3. Repartition(De)compositionLargely ignored in this paperConsider at least three communicating processesDesign ExampleWhatSoftware thread sending packets through a hardware transmitterAsynchronous Transfer Mode (ATM)HowCommunication through bus (PCI, EISA, or PI)Single byte transmission or burst mode?Cheetah SimulatorEvent drivenBuilt with communication platformsCheetah Simulator (II)At most abstract level, channel has a simple delayWith more detail, expands in both space and time Simulation speed varies from 7x to 175x RTLFuture InroadsBetter modeling and design explorationCan mix and match communication and behaviorsBetter synthesisAllows design reuseImproves don’t care extractionComposeabilityFuture Inroads (II)VerificationAbstraction and Decomposition are necessaryCan be used between steps in communication platformFormal specification allows test
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